Means for protecting contacts of electric switches



May 13, 1930. Y c. w. KUHN 1,758,752

MEANS FOR PROTECTING CONTACTS OF ELECTRIC SWITCHES Filed Feb. 7, 192'INVEN TOR.

gla/vMMW.W1 rv ATTORNEY Patented May 13, 1930 UNITED STATES PATENTOFQFICE,

CLARENCE W. KUHN, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESN-E ASSIGN-MENTS, TO CUTLER-HAMMER, INC.

, A CORPORATION OF DELAWARE J MEANS non .rno'rnorme containers onnnnc'r'nro swrronns Application fl led February 7, 1927. Serial No.166,487.

This invention relates to imprqvements in means for protecting contactsof electric switches, and the invention moreparticular ly relates to theprovision of improved means. for protecting relatively movable contactsof a switch from the destructive infiuence of arcs drawn therebetween.

It is customaryto provide one or both of the relatively movable contactsof a switch 10 with an arcing horn of shoe to receive and provide fordisruption of the are developed by'opening of said contacts, anelectromagnetic blow-out device being usually employed 9 to effect orexpedite passage of the are from the contacts to the arcing horns.Moreover,

such arcing horns have usually been formed of steel or brass, whereas'in practice it is found that the contacts in conjunction with whichsuch arcing horns are employed are subjected to severe destructiveinfluences of the are, so that the contactsrapidly become destroyed andrnust be frequently renewed;

I have discovered that by providing for shifting of the are from one orboth of the contacts to an arcing element or elements of relatively highmelting point the vapor. of which does not readily conduct the currentthe life and usefulness of such contacts will be M very greatlyincreased, thereby minimizing the amount of time, labor and materialrequired to keep the switch in proper ,working condition. I V i I Z/ Anobject of the invention is to provide arcing elements of such characterand construction as to greatly increase the'life of switch contactsassociated therewith.

Another object is to provide for utilization of aknown commercial alloyin constructing 1 said improved arcing elements.

Another'object is to provide an improved 1 structure of theaforementioned character ,vgh'ich may be readily and economicallymanufactured. i

(Other objects and advantages of the inven tion will hereinafter appear.

The accompanying drawing illustrates cer tain embodiments of myinvention which willfnow be described, it being understood thatvariouschanges in details may belnade without departing from the spirit andscope h of the invention as defined by the claims.

In the drawing, Figure 1 illustrates the contacts ofa conventional formof switch, said contacts having my improved arcing horns or elementsassociated therewith.

Fig. 2 is asimilar view of a modification in which but one of myimproved arcing elements is employed, and

Fig. 8 is a similar view of another modification embodying. myinvention.

Referring first to the device illustrated in .Fig. 1, the numerals 5 and6 designate the usual contacts of an electric switch, contact 5 beingcarried by a stationary support 7 and contact 6 being supportedbymember8 for movement into and out of engagement with said contact 5. Member 8is preferably so operated as to provide for final separation of contacts5 and 6 at the tips 5 and 6 whereby the normal contacting surfacesthereof are protected to a certain extent from influence of the aredeveloped upon separation of the contacts. Electrically and mechanicallyunited with each of said contacts is an arcing horn or element 9 of anyusual or preferredform. Assuming provislon of an elect-romagneticblow-out device for the switch, the same, is adapted upon separation ofthe contacts to transfer or shift the resulting arc fromrsaid contaptstd the arcing-elements 9,

with-consequent attenuation and extinguishment of the arc'after a giventime interval.

As aforeindicated, however, if the arcing elements 9 are formed in theusual manner from steel. brass or similar material it is" found that Ythe contactsare severely attacked by the arcs resulting from separationthereof, so that after service for acomparatively short time the sameare rendered unfit for further use and must therefore bereplaced by newcontacts.

On the other hand if the arcing elements are formed of amaterial of thecharacter dis closed herein it has been found that the life of suchcontacts is increased from fifty to bne hundred per cent or more; thusachieving a desirable economy in the upkeep andrepair of the switches.More sipecifia'ally,the mate- ,rial of which the arcing elementsareformed 1 spending parts are given like characters ofpreferablycomprises an alloy composed prin-' cipally of nickel and chromium, inthe pro-- portions of about eighty per cent nickel and reference;whereas it will be noted that only the stationary contact 5 is providedwith a "so-called arcing element,thus requiring attenuation andextinguishment of the are between the tip 6 of. contact 6 and theelement 9. However, it is found that by forming element 9 of theaforedescribed alloy of nickel and chromium the life of both contacts ofthe switch is materially increased or extended, as compared with that ofcontacts having the ordinary arcing element or elements associatedtherewith. The use of such alloy in this case likewise renders possiblethe more nected to ,said contacts, said elements being composed of anickel chromium alloye- 3. The combinationwith relatively movable switchcontacts, of arcing elements therefor composed of the nickel chromiumalloy nichron e.

4. The combination with relatively moyable switch contacts, at least oneofsaid contacts having an arcing element mechanically and electricallyconnected thereto, said element comprising an alloy of about twent percent chromium and eighty per cent nicke 5. The combination withrelatively movable switch contact members, of arcing elements integrallyunited therewith mechanically and electrically, said elements consistngof the nickel chormium alloy nichrome. I

6. The combination with a pair of relatively movable switch contactsformed of con.- ducting material of relatively low resistance, of arcingtips integrally united with said contacts b welding, said arcing tipsconsisting of an a loy of nickel-and chromium.

In witness whereof, Lhave hereunto subscribed my name.

CLARENCE w. KUH'N'.

rapid extinguishment of the arc,-due probably to the resulting higherresistance value of the arc vapor.

Fig. 3' illustrates a modification wherein the supports 7 and -8 carrycontacts 10 and 11,

respectively, of slightly diflerent construction. Thus said contacts'mayeach comprise a body portion formed in the usual manner from copper or acopper alloy of relatively low resistance, whereas each; of saidcontacts is provided with a tip 9 of the aforementioned alloy. Thus uponopening of the contacts 10 and.-11 the resulting arc will be initiallydrawn between the alloy tips or elements 9, so that the contactingsurfaces of the contacts are unusually well @protected from destructiveinfluence of the arc. The tips 9 are preferably integrally united withthe body portions of the contacts 10 and 11 in any suitable or wellknown manner, as by welding or brazing. By employment of a device likethat shown in Fig. 3 thenecessity for the provision of separatearcing'elements is obviated, whereas the over-all dimensions of theswitch structure may consequently be somewhat reduced.

' \Vhat I claim as new and desire to secure by Letters Patent is:

1. The combination with prising analloy. of 'nickel and chromium.

'2; The combination with a pair of relatively movable switch contacts,of' arcing ele- '-ments-associated w1th and electrically conrelativelymovable swltch contacts, of an arcing-element as- 'sociated with saidcontacts, said element com-

